To the point: I'll be performing a fuel pump pressure test at the pump tomorrow. The pump has a pressure and a return line; which is which? I don't want to undo more than I have to!

Also, today I tested fuel pressure at the test port. Cranking it got up to 30-40 psi, quickly cycling the key on and off got up to 45-ish, with it quickly falling to around 20 almost immediately after.

So I've obviously got a fuel problem. What are my odds that I got lucky and it's just the regulator, verses the pump? In January of this year I installed a new AC Delco pump and filter, new nut kit, and a cheap re-manufactured spider/regulator assembly.

Thanks for any help!

 

to test just the pump, disconnect the fuel filter and test there.

https://blazerforum.com/forum/tech-a...agnosis-23038/

 

I thought of that, but the test kit I rented didn't have a fitting the right size for the filter. Or at least one that looked like the right size. I might try anyway, but I think I'll have to connect to the pump. Somewhere along the way, the previous owners took it to some shade tree to replace the pump. Apparently they jacked up the pump fittings and sawed it off and clamped rubber hose between the fuel line and pump. So adapting something to that should be fairly easy provided it is the feed and not the return line.

 

So, I decided to throw some money at the thing. Too lazy to get the proper fittings to check the pump, I went ahead and bought a new fpr. It couldn't be my 11 month old Delco fuel pump, anyway, could it?

Well, with the new regulator, now I'm getting 0 psi. Finally got the stuff to isolate the pump. Key on, goes up to 40 quickly, then instantly to 0 when pump quits running. Now after an hour or so, it only can get up to 15 psi, after several key cycles.

I'll say again, this was a brand new, AC Delco pump from rock auto. It's less than a year old, and under 10k miles on it. Any ideas why it failed?




edit: by the way, I checked at the pump, not the filter. So it's nothing as simple as a clogged filter. Which is Delco as well, and was installed the same day as the fuel pump,

 

first thread for a long time on a bad pump from ac delco. strange. If you still have the receipt i was told they have a lifetime warranty. Not sure if its true. If you changed the spider,and its not leaking then you have a bad pump.

 

I thought it was strange too. everyone on here raves about them. Oh well, hopefully the new one lasts longer.

On rockauto's site, it shows them as having a one year warranty. I ordered it on jan 4 of this year, so I'm just barely in that.

 

call them and see what they wanna do.

 

Ok. Still having problems. I put in another new Delco pump today. Still won't start. Tested pressure at the manifold and while cranking it gets up to around 50. After I stop I hear the pump run and it holds around 50. When the pump stops, pressure quickly drops to around 15. Just turning the key on does nothing. There is no increase in pressure till I crank it. I already tried a new regulator before I changed the pump, and it did nothing so I returned it. I saw no evidence of washing in the plenum when I was changing the regulator.

Since all the mechanical parts are new, what are the chances of this being an electrical problem? Would a bad relay cause something like this? I'll search for threads on how to check voltage at the pump, but if someone knows off the top of their heads, that would be great.

I'm tired of working on this thing! I love the blazer but this is ridiculous! Plus, my daughter goes back to school Monday, so my wife will need her car back . Thanks for any help.

 

gotta be bad electrical connection or blocked fuel filter maybe? check ground wire at crossmember


maybe you should do the pump pressure check at the filter, to rule out the chance of having a bad pump again. that bleed off thing got me worried some, then if its good you can go straight to the injection spider.

 

Yeah, I plan on checking at the pump tomorrow. The filter is less than a year old but I need to check it too.Not holding pressure has me worried too.